edit: $/Dev10/feature/vs_langs01_s/Merlin/External.LCA_RESTRICTED/Languages/IronRuby/yaml/IronRuby.Libraries.Yaml/Engine/BaseConstructor.cs;C1040664
File: BaseConstructor.cs
===================================================================
--- $/Dev10/feature/vs_langs01_s/Merlin/External.LCA_RESTRICTED/Languages/IronRuby/yaml/IronRuby.Libraries.Yaml/Engine/BaseConstructor.cs;C1040664  (server)    11/3/2009 11:56 AM
+++ Shelved Change: $/Dev10/feature/vs_langs01_s/Merlin/External.LCA_RESTRICTED/Languages/IronRuby/yaml/IronRuby.Libraries.Yaml/Engine/BaseConstructor.cs;cul
@@ -19,6 +19,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Globalization;
 using System.Text.RegularExpressions;
 using Microsoft.Scripting;
 using Microsoft.Scripting.Runtime;
@@ -605,12 +606,12 @@
                 int bes = 1;
                 double val = 0.0;
                 for (int i = 0, j = digits.Length; i < j; i++) {
-                    val += (double.Parse(digits[(j - i) - 1]) * bes);
+                    val += (double.Parse(digits[(j - i) - 1], CultureInfo.InvariantCulture) * bes);
                     bes *= 60;
                 }
                 return sign * val;
             } else {
-                return sign * double.Parse(value);
+                return sign * double.Parse(value, CultureInfo.InvariantCulture);
             }
         }
 
===================================================================
edit: $/Dev10/feature/vs_langs01_s/Merlin/Main/Languages/Ruby/Libraries.LCA_RESTRICTED/BigDecimal/BigDecimal.cs;C802353
File: BigDecimal.cs
===================================================================
--- $/Dev10/feature/vs_langs01_s/Merlin/Main/Languages/Ruby/Libraries.LCA_RESTRICTED/BigDecimal/BigDecimal.cs;C802353  (server)    11/1/2009 11:02 PM
+++ Shelved Change: $/Dev10/feature/vs_langs01_s/Merlin/Main/Languages/Ruby/Libraries.LCA_RESTRICTED/BigDecimal/BigDecimal.cs;cul
@@ -16,6 +16,7 @@
 using System;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
+using System.Globalization;
 using System.Text;
 using System.Text.RegularExpressions;
 using Microsoft.Scripting.Math;
@@ -203,8 +204,12 @@
 
         #region Create Methods
         public static BigDecimal Create(Config/*!*/config, object value) {
+            Debug.Assert(!(value is double) && !(value is float)); // Need to use CultureInfo.InvariantCulture for double
             return Create(config, value.ToString(), 0);
         }
+        public static BigDecimal Create(Config/*!*/config, double value) {
+            return Create(config, value.ToString(CultureInfo.InvariantCulture), 0);
+        }
         public static BigDecimal Create(Config/*!*/config, string value) {
             return Create(config, value, 0);
         }
@@ -236,7 +241,7 @@
                 if (!fraction.IsZero) {
                     if (!string.IsNullOrEmpty(exponentStr)) {
                         try {
-                            exponent = int.Parse(exponentStr);
+                            exponent = int.Parse(exponentStr, CultureInfo.InvariantCulture);
                         } catch (OverflowException) {
                             exponent = exponentStr.StartsWith("-") ? -1 : 1;
                             return ExponentOverflow(config, sign, exponent);
@@ -326,7 +331,7 @@
                 if (BigDecimal.IsNegativeZero(x)) {
                     return -0.0;
                 }
-                return Double.Parse(x.ToString(0, "", true));
+                return Double.Parse(x.ToString(0, "", true), CultureInfo.InvariantCulture);
             } catch (OverflowException) {
                 return Double.PositiveInfinity;
             }
===================================================================
edit: $/Dev10/feature/vs_langs01_s/Merlin/Main/Languages/Ruby/Libraries.LCA_RESTRICTED/Builtins/StringFormatter.cs;C1162930
File: StringFormatter.cs
===================================================================
--- $/Dev10/feature/vs_langs01_s/Merlin/Main/Languages/Ruby/Libraries.LCA_RESTRICTED/Builtins/StringFormatter.cs;C1162930  (server)    11/1/2009 11:01 PM
+++ Shelved Change: $/Dev10/feature/vs_langs01_s/Merlin/Main/Languages/Ruby/Libraries.LCA_RESTRICTED/Builtins/StringFormatter.cs;cul
@@ -413,7 +413,7 @@
 
                 // One digit is displayed before the decimal point. Hence, we need one fewer than the precision after the decimal point
                 int fractionDigitsRequired = (_opts.Precision - 1);
-                string expForm = absV.ToString("E" + fractionDigitsRequired);
+                string expForm = absV.ToString("E" + fractionDigitsRequired, CultureInfo.InvariantCulture);
                 string mantissa = expForm.Substring(0, expForm.IndexOf('E')).TrimEnd(zero);
 
                 // We do -2 to ignore the digit before the decimal point and the decimal point itself
===================================================================
edit: $/Dev10/feature/vs_langs01_s/Merlin/Main/Languages/Ruby/Ruby/Hosting/RubyOptionsParser.cs;C1221149
File: RubyOptionsParser.cs
===================================================================
--- $/Dev10/feature/vs_langs01_s/Merlin/Main/Languages/Ruby/Ruby/Hosting/RubyOptionsParser.cs;C1221149  (server)    11/1/2009 10:17 PM
+++ Shelved Change: $/Dev10/feature/vs_langs01_s/Merlin/Main/Languages/Ruby/Ruby/Hosting/RubyOptionsParser.cs;cul
@@ -298,6 +298,14 @@
 #endif
             LanguageSetup.Options["SearchPaths"] = _loadPaths;
             LanguageSetup.Options["RequiredPaths"] = _requiredPaths;
+
+#if DEBUG && !SILVERLIGHT
+            // Can be set to nl-BE, ja-JP, etc
+            string culture = Environment.GetEnvironmentVariable("IR_CULTURE");
+            if (culture != null) {
+                System.Threading.Thread.CurrentThread.CurrentCulture = new System.Globalization.CultureInfo(culture, false);
+            }
+#endif
         }
 
         public override void GetHelp(out string commandLine, out string[,] options, out string[,] environmentVariables, out string comments) {
===================================================================